It is common in the field of horology to manufacture electronic watches, an example embodiment of which is shown in FIG. 5. Such a watch 50 conventionally comprises a case 51 including a back cover and closed on top by means of a glass, said case containing a watch movement controlled by an electronic circuit, that are not shown, a dial 52 carrying time indicating means, for example hands 53 driven by the gear trains of the watch movement. Dial 52 includes an aperture 54 for making visible display means 55, such as for example a liquid crystal display or LCD.
Traditionally, display means 55 are mounted on a support piece, not visible in this Figure, disposed underneath the dial and fixed with respect thereto. The support piece includes a pattern cavity for receiving display means 55 and positioning them in relation to aperture 54 made in dial 52 so that they are visible through dial 52 via aperture 54. Once display means 55 have been positioned in the pattern cavity provided for such purpose, a light guide or a holding plate is placed on top then sealed onto the support piece preventing any movement of display means 55 along an axis perpendicular to the mid-plane of the support piece.
There is also known from the prior art, particularly from U.S. Pat. No. 4,218,872, a watch comprising a stop element used for determining the position of the dial in relation to that of an electro-optical cell. It will be noted however that no mechanical means are provided that can be actuated by a user in order to move the display means against the stop element.
Nonetheless, it has been observed that the conventional methods for positioning display means 55 do not, on the one hand, allow precise positioning of the display means to be obtained in relation to aperture 54 made in watch dial 52, particularly because it is necessary to have a play between the size of the pattern cavity and display means 55 to prevent any excessive mechanical stress on the latter, and, on the other hand, such methods do not allow the position of said display means to be maintained properly during the operation of securing of the light guide.
In these conditions, the securing operation is thus carried out with approximate positioning of the display means. Thus, a certain number of watches 50 have a dial 52 with an aperture 54 through which display means 55 are visible positioned askew, which consequently greatly affects the aesthetic appearance of such watches, which is evidently undesirable. It is also undesirable to keep only those watches having a suitable aesthetic appearance at the prices of significantly decreasing the production line yield.